Continental Asia's longest-lost bird? The taxonomic and conservation status of the Ayeyarwady Broadbill Cymbirhynchus [macrorhynchos] affinis

A recent proposal to treat Ayeyarwady Broadbill Cymbirhynchus [macrorhynchos] affinis of south-west Myanmar as a species separate from Black- and-red Broadbill C. macrorhynchos has failed to garner widespread support. Here we compare six specimens of affinis with a large series of C. macrorhynchos and glean what information we can from specimen data and the literature about this poorly known taxon's distribution and conservation status. C. affinis differs in being 10–17% smaller, with a 22% shallower bill, and having elongate crimson spots on the tertials, a much larger white wing spot, paler and brighter red on the underparts and rump, and broader and more extensive white subterminal tail tips. In our view these characters, which represent abrupt and profound differences across a trivial distance from the nearest population of the wide-ranging and (as we argue) probably monotypic C. macrorhynchos, uphold species rank for the taxon. However, we can find no record of it since 1874. It may once have occurred throughout the Ayeyarwady Delta, where it may now be extirpated due to the near-total loss of suitable habitat. It has also been recorded in the Rakhine Yoma (Arakan Hills) up to an elevation of at least 750 m, where suitable habitat remains, although recent (untargeted) field work has not found it there. However, the meagre evidence for its former range and status is disconcertingly inconsistent. We recommend that Ayeyarwady Broadbill be listed on the IUCN Red List as Data Deficient.